Method of making air gas



1624,046 April 12 1927' H. FOERSTERLING METHOD OF MAKING AIR GAS FilMarch 28. 1925 y- INVENTOR,

, neously. I

Patented Apr. 12, 1927.

Lamas :Y D T EN omce.

.IELA-NS FOEBSTERLING, OF JAMESBUBG, NEW JERSEY.

METHOD OF MAKING AIR GAS.-

Application med March 28,1925. Serial No. 19,167.

The invention relates to an improved method of making air gas.

In my copending application Serial No. 13,068, entitled Method of makingair gas, filed by me on the 5th day of March, 1925, I have described amethod of making air gas by vaporizing with air volatile inflammableliquids, or partially sufiioient vapor tension to form with air atatmospheric temperatures an ignitable air as which will burn homo eavealso described a suita 1e apparatus for carrying out ,this method,

which apparatus is set forth and claimed in m .U. S. Patent No.1,601,303, dated September 28th, 1926.

.In-my copending application Serial No.

13,069, entitled Method of producing air gas, filed by me March 5th,1925,I have described a method ofmaking air gas byrvaporizing with airvolatile inflammable liquids, which either have mospheric temperaturesan ignitable air gas g and sets forth in detail how from such liquids anair gas can be produced which will'burn' either homogeneously orheterogeneously.

M invention will be more fully understoo from the consideration ofcertain physical and chemical properties of air gas producing compoundsof liquid form, which properties play an important-role in my invention.

By dividing the molecular, weight of a compound by the factor 28.94:,which represents the assumed molecular weight of the g air, I calculateits vapor density, which may be designated a.

Hence one liter vapor of any particular compound will weigh at 10 C.1.248 grams times a.

By dividing the vapor tension of such compound at 10 C. by 760, I obtainthe volume per cent of the vapor in air, which I call I).

Hence a times I) "gives the number of grams ound which can he vaporizedtheoretically at 10 C. per one cubic meter.

times 1.24.8 times 10 which either have 511111016115 sufiicient or partially sufficient vapor tension to form with f I from which can becalculated that: 97.5 grams of such com-' alcohol or ethyl alcoho Thefollowing table is compiled on basis of this calculation, the 'followinvapor tengiven in mil imeters and sion figures being eing taken fromLandoltrefer to 10 C Bornstein, Physikali'schechemische 'Iabellen,

Verlag von Julius Springer, Berlin, 1905.

Complete combustion is governed by the i following weight equations:

v v v 1 Grams v 1. apolspot 0 per one 0 Formula. figzff dentenume cubica? city. sion. meter I 1 of gas.

Methyl-alcohol CHaOH 32 L 105 53.8 7.18 97.5 92.92 Ethyl-alcohol z 46 1.59 24. 08 3. 17 62. 8 96. 83 Ether (0111910 74 2. 286. 8 37. 7 1210 62.3 Acetone CHxCOCHu- 58 2. 02 11. 85 296 88. 15 Benzo1CH@. 78 2.69 $5.255.96 200 94-04 a. 1000 liters gas containing methyl alcohol in vaporform=70.8 liters will require for com lete combustion 109.5

rams O; the remaining 929.2 liters air contain at 10 C. (assuming 20.9volume O at 1.38 grams) 267.5 grams 0 or 158 grams 0 are in excess. b.1000 liters gas containing 62.8 grams a 107 grams 0 are in excess. w

containing .1200 grams 0. 1000 liters of gas ether in vapor form-4377liters will require .90 ethyl alcohol in vapor form:;31.7 liters'will3135 grams 0, while the remainin 623liters: I of air contain only 17 9.5grams or 2995.5

rams O are lacking.

cl. 1000 liters of gas containing 296 lame acetone in vapor .form:118.5liters will re-.

quire 654 grams 0, while the remainin 881.5 liters of air contain only253 grams or 401 grams O'are lacking.

e. 1000 liters of gas containing 200 ams benzol in vapor form=59.6liters wil require 616 grams 0, while the remainin 940.5 liters of aircontain only 270 grams or 346 grams O'are lacking.

It will be obvious from these calculations why an air gas made 1)vaporizing methyl-- with air at 10 0.,

will not burn, whereas an aii -ether, air-acetone or air-benzol gas willburn.

Of the latter three, the air-acetone and airbenzol mixtures are ofspecial interest.

According to the equation:

58 grams acetone require 128 grams oxygen which are contained in 4&3liters of air at 10 C. As 1 liter of acetone vapor weighs 2.5 gramshence 58 grams acetone correspond to 23.2 liters of vapor; or a mixtureof '443 liters of air containing 128 grams 0 23. 2 liters acetonevapor==58 grams acetone 466. 2 liters C., at which temperature itamounts to 179.6

Y which figure 1 have assumed in mm. Plotting however a curve from thepublished data of higher temperatures I derive the vapor tension of 90mm. for 10 C.,

my calculations as approximately correct. It will be obvious that anair-acetone mixture having a vapor tension of only 37.8 mm. can be exposed to a temperature below 0 C. without condensing any acetone vapor.The same mixture corresponds to 3.7 grams acetone or 4.6 cc. per 28.3liters of air.

I will now describe one method of carrying out my invention usingacetone as the raw material for the production of air gas and by meansof a suitable apparatus, the features of which will be more fullyunderstood from the following detail description and the accompanyingdrawings, in which the figure is a view, largely in vertical section andpartly in side elevation, of one form of apparatus in which my inventionmay be carried out.

Referring to the figure, 1 represents a fan or blower as is commonlyused in the manu-' facture of air gas; the fan or blower 1 is providedat its back with an air intake (not shown) and at its front with anaxle, connected by suitable means such as the winch 2 actuated by thecounterweight 3 by means of the wire rope 2 wound on the winch 2. On theshaft 1 of the internal wheel of the fan or blower, I mount the sprocketwhg'eel 1 which drives by means of a chain 4% the sprocket wheel 5keyed. to or otherwise fixed on one end of the countershaft 6. At theother end of the countershaft 6 is seci red the eccentric or cam 7. Thehub of the cocentric 7 is regulated by any suitable means, therebycontrolling the proportion of the air to the acetone to be vaporized, asappears more fully hereinafter. The eccentric 7 drives by means of thelever 11, tlm rock shaft 12 and lever 11 the piston (not shown) of thepump 14. 15 represents a storage tank for the inflammable liquid,located preferably underground. The tank 15 is provided with a breatherpipe 16 which serves at the same time as its filling means uponunscrewing the bend 17. The tank 15 is connected with the pump 14 bymeans of the pipe line 18, which is provided at its end within the tank15 with the foot valve The overflow 20 of the pump 14. see Fig. 1, isconnected with the coil 21. The lower end of coil 21 is connected bymeans of the air line 25 with the outlet of the fan or blower 1. Bymeans of the pipe line 26 the bottom of the coil 21 is connected withthe overflow tank 27. The tank 27 collects any moisture and otherimpurities of the acetone, and similarly for other volatile inflammableliquids pursuant to my invention; the tank 27 is emptied as required byunscrewing the bend 28 from its breather pipe 29, to permit a pump to beinserted through the pipe 29 and into the tank. The pipe line 26 issealed within the tank 27 against the flow of the gas by means of'itsseal 30. The gas main 31 is connected to the upper end of the coil 21 asshown and is provided with a test burner 32.

The cook 33 controls the air line 25 leading to the coil 21. The cook 34controls the main gas line 31 and the cook 35 controls the test burner32.

The casing of the blower or fan 1 is filled with a suitable sealingfluid to the desired erwise. The cock 35 of the test burner 32 is nowopened. The blower or fanl is set into motion and at the same time thepump 14 through the gearing, including the sprocket wheels 4 and 5 pumpsacetone from the tank I 15 into the coil 21.

Upon regulating the pump 50- that approximately 5.6 ccm. of acetone per28.3 liters of air are passed through the coil 21, I obtain a gas whichburns with a' green inner core, surrounded by a blue outer mantle. Theacetone is thereby completely vaporized. with the exception of moistureand other inipurities contained therein.

Using the same grade of acetone and passing it through the aforesaidapparatus above referred to, but burning the mixture of air and acetonevapor so produced under conditions suitable for heterogeneous combustionas described in my aforesaid copcnding application. Serial No. 13,069,and using the burner described pursuant to mv method set forth in mycopending application Serial No. 57,996, filed by me on the 23rd day ofSeptember, 1925, and entitled Method of heating, I have discovered thatI require only 3.7 ccm. of acetone per 283 liters'of air.

Ihe theoretical calculation for benzol gives the following data:

According to the equation:

832 liters of air containing-240 grams oxygen 23. 2 liters of benzolvapor containing 78 grams benzol 855. 2 liters constitute the properproportions. Such a gas corresponds to 2.71 vol. or a vapor tension 'of20.6 mm. .As the vapor tension of benzol as 0 C. has been determined atd 26.54 mm., it is clear that the above air-benzol gas mixture may alsobe exposed to a freezing temperature without risk of any condensation inthe pipe lines.

. 78 grams benzol per 832 liters of air correspond to 2.65 grams whichis the equivalent of 3 com. per 28.3 liters of air.

Using a pure benzol having 2. sp. gr. of .887 at 9.5 C. and duplicatingthe experiments described above for an air-acetone gas I find that I useunder the conditions suitable for homogeneous flame combustion 3.5 com.and for heterogeneous surface combustion 2.3 ccm. per 28.3 liters ofair.

Using a 90% benzol I required 3.1 com. for homogeneous flame combustionand 2.5 com. for heterogeneous surface combustion. 1 In all four teststhe benzol was completely vaporized.

It will be obvious from the above that in flammable liquids other thanacetone or benzol may be used in connection with the aforesaid methodand my aforesaid apparatus described in my aforesaid copendingapplication, Serial No. 13,068 and that they shall serve only as anexample for demonstrating the requisites which have to be complied to.

90% benzolis sold todayat 23 cts. per gaLagainst about. 20 cts. formotor gasoline; hence its price is not excessive for-heating andilluminating purposes in connection.

with my aforesald apparatus.

Benzol being completely vaporized, andcheaper than the so-called gasmachine gasoline, and also at much less risk in handling and storing,from the explosion standpoint, than gasoline, it is especially adaptedfor the houshold which has no use for the un vaporized residuev of motorgasoline for power purposes.

Benzol is a by-product of tar distillation and'of coking processes andis produced in increasing quantities.

rial for instance such as maize.

price of acetone, (fermentation acetone be- Acetone is obtained by drydistillation of acetate of lime, and also as a by-product of wooddistillation. It can also be obtained by fermentation of starchcontaining matelVhile the ing quoted today at 10 cts. per lb.) seems tobe high, it is in so far of interest that it can be produced from plantmatter and may be for that reason of more importance in the future;

For the reasons previously stated it has always been consideredimpossible to use the lower alcohols, especially ethyl alcohol,

for the purposeof'producing an air gas.-

Artificial heat would not help any, since the low vapor tension thesesubstances possess would tend towards condensation in-the pipe lines. Ihave found however that I can also use these lower alcohols for theproduction of air gas by mixing them with other volatile inflammableliquids, if I follow certain considerations which I describe in thefollowing. 5

I have shown that a gas mixture containing 70.8 liters 'of methylalcohol vapo": 97.5 grams methyl alcohol and 929.2 liter; of air has 158grams 0 in excess over what is required for the complete combustion-ofthe alcohol. I

I have also shown that a gas mixture containing 118.5 liters of acetone.vapor:2 96 grams of acetone and 881.5 liters of air is lacking 401 grams0 for the complete combustion of its acetone content.

I By adding to the air vapor mixture showmg a deficit of oxygensufficient of an air vapor mixture possessing a surplus of oxygen, orvice versa, I derive a balanced airper 1000 liters of air at 100 C. arecomputed from the following factors 1000 liters of gas contains 97.5grams of methyl alcohol with 158 grams of oxygen in excess. Furthersince 1000 liters of gas contain 296 grams of acetone with 401 grams ofoxygen deficit, it follows that 394 liters of gas contain 116.5 grams ofacetone with 158 grams of oxygen deficit.

Therefore I will obtain a balanced air--- gas which will vaporizecompletely at 10 (1., by mixing 97.5 grams methyl alcohol ture throughmy apparatus as hereinabove' with 116.5 grams acetoneand pass thismixdescribed.

1000 liters of gas containing 97.5 grams CH,O:7.08 vol. and 929.2 litersof air and 394 liters of gas containing 116.5 grams (1 11 021185 vol.and 347.4 liters of air alcohol and 2.58 ccm. of acetone, i. e., a totalliters of air, I use of 5.19 ccm. of the methyl alcohol-acetone mixtureper'28.3 liters of air.

Based on the same considerations I have calculated that 1000 literscontaining 62.8 grams ethyl. alcohol with 107 grams O in excess and 268liters containing 79.5 grams acetone with 107 grams 0 deficit will'iurnish a balanced gas.

Since such a, mixture contains 1204.3 1.475 grams ethyl alcohol +1866grams acetone.

this mixture per 28.3 liters of air.

I have prepared a mixture of methyl alcohol and acetone as abovecalculated, using a. 95% methyl alcohol of a sp. gr. of .83 and atechnical acetone testing .82 sp. gr. at 0 C. and ran the same throughmy aforesaid apparatus and obtained an air gas which burns with a goodflame, showinga reen inner core surrounded by a blue mant e. I

tone, which can amount of hardwood is substantially the the li alsofound that the mixture was complete- 1 vaporized. Using theheterogeneous surace combustion burner previously referred to, I foundthat I consumed 5 com. of this mixture er 28.3 liters of air against thetheoretica ly calculated amount of 5.79 ccm. showing that I can use alean gas which corresponds with former. experience.

A mixture of methyl alcohol-l-acetone is in so far of special interestas both term by-products of the wood distillation process and theroportion of methyl alcohol to acebe obtained from a given same as theone stated above.

When employing methyl alcohol and acetone as the liquids to bevaporized, I can either employ separate reservoirs and pumps for therespective liquids each pump being connected to the vaporlzer of myaforesaid apparatus, said pumps being controlled by individual cams, orI can mix uids in the desired proportion and procee according to themethod and apparatus described and claimed in my co-pendria No.

in applications Serial No. 13,068 and Se- 61,816, respectively.

It is obvious that for my purpose it is not necessary to have pureproducts. Some oi the chief ingredients in. the raw wood alcohol besidesmethyl alcohol are acetone and I add 116.5 grams of ace- That is to say,1.83v 'ccm.+2.3 com. or a total of 4.13 ccm. of

' gas does not have to possess a like one which is used in themanufacture of heterogeneous sideration for my process,

methyl acetate, important data for acetone have already been given..Methyl acetate has the formula C,H O CI-I its molecular weight is 74,and its vapor density is 2.55. Its vapor tension amounts to 62.1 mm. at0 mm. at 10 C. Hence at 0 C. 8.18 vol. and at 10 C. 13.8 vol. are takenup. complete quired per one molecule methyl acetate.

' From this data and the previous given data for acetone it will be seenimpurities of raw wood as far as its use for that the principal theproduction of air gas is concerned and that it is preferable to in andmerely conleave these impurities centrate the raw wood alcohol bydistillation.

As toda s cost of methyl alcohol is largely so igh on account of thecost 0 urification, which is an expensive process, 1518 obvious thatsuch an impure product as is desirable for my process can be produced ata considerably lower figure.

Mixtures of methyl alcohol and acetone simple re- Forcombustion 7molecules 0 are re and also aldehydes/ The 1 C. and 104.85

alcohol are desirable have also been produced simultaneously by the drydistillation of black liquor resu ing from the soda pulp industry.

What I have,sa1-d in regard "to the 'requirements of a methyl alco 01for the purpose of producing an air gas prevails also for acetone.suitable for use in the manufacture of air purity as powder or forextraction purposes.

I have further prepared a mixture of ethyl alcohol and acetone inconformity to the previously referred to theoretical calculation, usinga denatured alcoholas sold for preventing automobile radiators fromfreezing in winter time and which tested .835 sp.-gr. at 0 G, indicatinga product of apfproximately purity.

I ound, using a burner suitable for surface combustion, that I can. ofsuch mixture per 28.3

consumed 5.1

It is obvious that an acetone,

liters of air against 4.13 ccm. as calculated.

It is obvious that with aliquid of-such the factthat approximately I lowvapor tension as ethyl alcohol possess at the temperatures which comeunder condepends on the time allowed for reaching the saturation maximumfor a given temperature. i

This was further periment carried out mixture illustrated by an exinwhich the samewas burned under conditions favorthe success of it ablefor homogeneous flame combustion, where a greater amount of liquid wassent throu h the apparatus in the" same time period. Inthis instance Iused 6.35 ccm. of the mixture per 28.3 liters of air and theunvapori'zed portion increased to 23.7%.

Still more pronounced was this factor .when I prepared a balancedmixture of ethyl alcohol and ether. Here extremes, meet, a compound ofenormous vapor tension is comb ned with one possessing a very low one;28.3liters of air at 10 C. takes up 54.6 grams ether but only 1.82 gramsethylalcohol. I

Passing such a mixture containing 212 com. of common denatured alcoholand 162 ccm. of ether through my apparatus, I used 6.4 ccm. per 28.3liters of air against 3.7 ccm. which I should use theoretically. Fromthe amount of recovered liquid I calculated that only approximately" 27%of the alcohol pasdsed through my apparatuswas vapor ize I v But tothose skilled-in the art it will be clear that even-such a mixture canbe used in connection with my process, provided the vaporizer is soconstructed as to atford a greater extent of counterflow and therebyprovide suflicient additional time for attaining complete saturationofthe air with the vapor of the liquid having a} low vapor tension.

In view of the fact that ethyl alcohol can be manufactured from plantmatter ata low price practically'ever where, that our resources ofgasoline are eclining and that the transportation of gasoline tocountries possessing no oil deposits increases its cost, the possibilityof its use for the purpose of producing an air gas seems to be veryimportant.

In countries where hydrocarbons such as gasoline or benzol are notproduced today,

asfor instance in the tro ics, which on theother hand possess an aundance of raw material for the manufacture of alcohol,

ether, acetone, and the like, mixtures of such compound 'seem to bedestined to solve the problem of an economic heating method forhouseholdpurposes.

It must be clearly understood that the compounds mentioned, the mixturesenumerated shall serve only the purpose of illus-f trating my inventionand that other volatile inflammable liquids filling the requirementsstated can be used, the mixtures of the compounds mentioned can bechanged in innumerable ways, other mixtures may be compounded.

Whereas, I have described-my invention 1 by reference to specific formsthereof, it will be understood that many changes and modifications maybe made without departing from the spirit of the invention; in certainof the appended claims wherein by reason pression in the claims methylalcohol is mentioned it is to be understood that such expression is notto be regarded as limiting such claims specifically to said alcohol. Anyother inflammable liquid which is volatile and does not possesssufiicient vapor tension under conditions of normal temperature to forman explosive gas mixture is to all intents and purposes an equivalent tomethyl alcohol. The term of methyl alcohol is hence to be regarded ofsuificient breadth to cover such equivalents and is. employed in thisfashion to avoid alternativeness in'said claims. y

'In certain of the-appended claims wherein by reason of the objection ofalternativeness, l have used the expression the total amount of oxygencontained in the final air inflammable vapor mixture shall not begreater than required by the combustible constituents for completecombustion it must be likewise understood to include also such acomposition wherein a slight excess of oxygen is present and which issuitable for heterogeneous combustion as described in my copendiugapplication Serial'No. 13,069. Hence-the above expression includes suchequivalent of composition and is employed solely to 'avoid,falternativeness in saidclaims. v v

I claim:

to. I

1. The method of making an air gas from an inflammable volatile liquidpossessing a vapor tension insufiicient to form with' air at atmospherictemperatures and low pressure an ignitable gas, which comprises mixingsuch volatile inflammable liquid with another volatile inflammableliquid posses sing a vapor tension sufiicient to form with air anignitable gas containing a deficit in oxygen content for completecombustion in such proportion that the total amount of oxygen containedin the air gas resulting 1o." quired for the complete combustion of thefrom such mixture'i's not greater than recombustible constituents ofsuch liquid mix-' ture, vaporizing such liquid mixture with air atatmospheric temperatures'and low pressure, and regulating the amount ofair accordingly. j I I 2. The method of making an air gas from aninflammable volatile liquid possessing a vapor tension insufficient toform with air at atmospheric temperatures and low .pressure an ignitablegas, which comprises mixing such volatile inflammable liquid withanother volatile inflammable liquid possessing p I a vapor tensionsufiicient-to form'with air an Went for complete combustion in such pro:

iguitable gas containing a deficitin oxygen" portion that the totalamount .of oxygen contained in the air gas resulting from .such

mixture is substantially that required for the complete combustion ofthe combustible a.

' rate of consumption of the resulting air- 3. The method of making anair gas from an inflammable volatile liquid possessing a vapor tensioninsuificient to form with air at atmospheric temperatures and lowpressure an ignitable gas, which comprises mixing such volatileinflammable liquid With another volatile inflammable liquid possessing avapor tension sufficient to form with air an ignitable gas containinga'deficit in oxygen from such'mixture is not content for completecombustion in such proportion that the total amountpf oxygen containedin the air gas resulting quired for the complete combustion of thecombustible constituents of such liquid mix ture, vaporizing such liquidmixture with air at atmospheric temperatures and 10W pressure incounter-directions while allowing suflicienttime to effect thevaporization of said first-named liquid jointly with said anotherliquid, and regulatingthe amount of air accordingly.

4. The method of making an air gas from an inflammable volatile liquidpossessing a vapor tension insuflicient to form with air at atmospherictemperatures and low pressure an ignitable'gas, which comprises mixingsuch volatile inflammable liquid with another volatile inflammableliquid possess ing a vapor tension sufficient to form with air anignitable gas containing a deficit in oxygen contentfor completecombustion in such proportion that the total amount of oxygen containedin the air gas resulting from such mixture is not greater than requiredfor the complete combustion of the combustible constituents of suchliquid mixture, vaporizing such liquid mixture in a vaporizer with airat atmospheric temperatures and low pressure, regulating the amount ofair accordingly and maintaining the temperature of the vaporizersubstantially constant. v

5. The method of making an air gas from an inflammable volatile liquidpossessing a vapor tension insuflicient to form with air at atmospherictemperatures and low pressure an ignitable gas,-which comprises mix--ing such volatile inflammable liquid with another volatible inflammableliquid possessing a vapor tension sufiicient to form with airanignitable gas containing a deficit in oxygen content for completecombustion in such proportion that the total amount of oxygen containedin the air gas resultin from suc mixture is not greater than requiredfor the complete combustion of the combustible congreater thanrestituents of such liquid mixture, vaporizing ing from the vaporizerany unvaporized portion of the liquid mixture.

6. The method of making an air gas from methyl alcohol which possesses avapor tension insufficient to form with air at atmospheric temperaturesand low pressure an ignitable air gas, which comprises mixing withmethyl alcohol another volatile inflammable liquid possesslng a vaportension sufficient to form with air at atmospheric temperatures and lowpressure an ignitable air gas containing a deficit in oxygen content forcomplete combustion in such proportion that the total amount of oxygencontained inthe air gas resulting from such mixture is not greater thanrequired for the complete combustion of the combustible constituents ofsuch liquid mixture, vaporizing such liquid mixture with air atatmospherlc temperatures and 'low pressure, and regulating the amount ofair accordingly.

7 The method of making an all gas from methyl alcohol which possesses avapor tension insuflicient to form with air at atmospheric temperaturesand low pressure an ignitable air gas, which comprlses mixing withmethyl alcohol another volatile inflammable liquid possessing a vaportension suflicient to form with air at atmospherictemperatures and lowpressure an ignitable air gas containing a deficit in oxygen content forcomplete combustion in such proportion that the total amount. of oxygencontained in the air gas resulting from such mixture is substantiallythat required for the complete combustion of the combustibleconstituents of such liquid mixture, vaporizing such liquid mixture withair at atmospheric temperatures and low pressure, regulating the amountof air accordingly, and maintaining such proportion of the air and suchliquid mixture independently of the rate of consumption of the resultingair gas.

8. The method of making an air gas from methyl alcohol which possesses avapor tension insufficient to form with air at atmospheric temperaturesand low pressure an ignitable air gas, which comprises mixing withmethyl alcohol another volatile inflammable liquid possessing a vaphrtension suflicient to form with air at atmospheric temperatures and low,pressure an ignitable, air gas containmg a deficit in oxygen con-' tentfor complete combustion in such pro portion that the total amount ofoxygen contained in the air gas resultin from such ing such liquidmixture'with air at atmospheric temperatures and low pressure incounter-directions while allowing sufiicient time to effect thevaporization of the methyl alcohol jointly with said another liquid, andregulating the amount of air accordingly.

9. The method of making an air gas from methyl alcohol which possesses aVapor tension insuflicient to form with air at atmospheric temperaturesand low ressure an ignitable air gas, which comprlses mixing with methylalcohol another volatile inflammable liquid possessing a vapor tensionsufiicient to form with air at atmospheric temperatures and low pressurean ignitable air gas containing a deficit in oxygen contentfor completecombustion in such proportion that the total amount of oxygen containedin the air gas resulting from such mixture is not greaterthan requiredfor the complete combustion of the combustible constituents of. suchliquid mixture, vaporizing such liquid mixture in a vaporizer with airat atmospheric temperatures and low pressure, regulating the amount ofair accordingly, maintaining the temperature of the vaporizersubstantially constant, and removing from the vaporizer any unvaporizedportion of the liquid mixture.

10. The method of making an air gas from an inflammable volatile liquidpossessing a vapor tension insufficient to form that the total amount ofoxygen contained in the air gas resulting from such mixture is notgreater than required for the complete combustion of the combustibleconstituents of such liquid mixture, vaporizing such liquid mixture withair at low pressure, and re lating the amount of air accordin 1y.

n testimony whereof I have signed this specification this 19th day ofMarch, 1925.

HANS Fo Rs'rnRLme.

